local mod = 1000000007 local mfl = math.floor local function bmul(x, y) local x0, y0 = x % 31623, y % 31623 local x1, y1 = mfl(x / 31623), mfl(y / 31623) return (x1 * y1 * 14122 + (x1 * y0 + x0 * y1) * 31623 + x0 * y0) % mod end local function badd(x, y) return (x + y) % mod end local function bsub(x, y) return x < y and x - y + mod or x - y end local function modpow(src, pow) local res = 1 while 0 < pow do if pow % 2 == 1 then res = bmul(res, src) pow = pow - 1 end src = bmul(src, src) pow = mfl(pow / 2) end return res end local function modinv(src) return modpow(src, mod - 2) end local fact = {1} for i = 2, 100000 do fact[i] = bmul(fact[i - 1], i) end local function getComb(n, k) if k == 0 or k == n then return 1 end return bmul(fact[n], modinv(bmul(fact[k], fact[n - k]))) end local n, d, k = io.read("*n", "*n", "*n") local ret = 0 k = k - n for id = 0, n do if k < id * d then break end -- get coef x^{id*d} of (1 - x^d)^n local coef1 = getComb(n, id) if id % 2 == 1 then coef1 = mod - coef1 end local rem = k - id * d -- get coef x^rem of (1-x)^{-n} -- (1-x)^{-n} = Sigma_a {Comb(a+n-1, n - 1)x^a} local coef2 = getComb(rem + n - 1, n - 1) ret = badd(ret, bmul(coef1, coef2)) end print(ret)